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 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 *
 */

package java.awt.image;


/**
 * This class defines a lookup table object.  The output of a
 * lookup operation using an object of this class is interpreted
 * as an unsigned byte quantity.  The lookup table contains byte
 * data arrays for one or more bands (or components) of an image,
 * and it contains an offset which will be subtracted from the
 * input values before indexing the arrays.  This allows an array
 * smaller than the native data size to be provided for a
 * constrained input.  If there is only one array in the lookup
 * table, it will be applied to all bands.
 *
 * @see ShortLookupTable
 * @see LookupOp
 */
public class ByteLookupTable extends LookupTable {

  /**
   * Constants
   */

  byte data[][];

  /**
   * Constructs a ByteLookupTable object from an array of byte
   * arrays representing a lookup table for each
   * band.  The offset will be subtracted from input
   * values before indexing into the arrays.  The number of
   * bands is the length of the data argument.  The
   * data array for each band is stored as a reference.
   *
   * @param offset the value subtracted from the input values before indexing into the arrays
   * @param data an array of byte arrays representing a lookup table for each band
   * @throws IllegalArgumentException if <code>offset</code> is is less than 0 or if the length of
   * <code>data</code> is less than 1
   */
  public ByteLookupTable(int offset, byte data[][]) {
    super(offset, data.length);
    numComponents = data.length;
    numEntries = data[0].length;
    this.data = new byte[numComponents][];
    // Allocate the array and copy the data reference
    for (int i = 0; i < numComponents; i++) {
      this.data[i] = data[i];
    }
  }

  /**
   * Constructs a ByteLookupTable object from an array
   * of bytes representing a lookup table to be applied to all
   * bands.  The offset will be subtracted from input
   * values before indexing into the array.
   * The data array is stored as a reference.
   *
   * @param offset the value subtracted from the input values before indexing into the array
   * @param data an array of bytes
   * @throws IllegalArgumentException if <code>offset</code> is is less than 0 or if the length of
   * <code>data</code> is less than 1
   */
  public ByteLookupTable(int offset, byte data[]) {
    super(offset, data.length);
    numComponents = 1;
    numEntries = data.length;
    this.data = new byte[1][];
    this.data[0] = data;
  }

  /**
   * Returns the lookup table data by reference.  If this ByteLookupTable
   * was constructed using a single byte array, the length of the returned
   * array is one.
   *
   * @return the data array of this <code>ByteLookupTable</code>.
   */
  public final byte[][] getTable() {
    return data;
  }

  /**
   * Returns an array of samples of a pixel, translated with the lookup
   * table. The source and destination array can be the same array.
   * Array <code>dst</code> is returned.
   *
   * @param src the source array.
   * @param dst the destination array. This array must be at least as long as <code>src</code>.  If
   * <code>dst</code> is <code>null</code>, a new array will be allocated having the same length as
   * <code>src</code>.
   * @return the array <code>dst</code>, an <code>int</code> array of samples.
   * @throws ArrayIndexOutOfBoundsException if <code>src</code> is longer than <code>dst</code> or
   * if for any element <code>i</code> of <code>src</code>, <code>src[i]-offset</code> is either
   * less than zero or greater than or equal to the length of the lookup table for any band.
   */
  public int[] lookupPixel(int[] src, int[] dst) {
    if (dst == null) {
      // Need to alloc a new destination array
      dst = new int[src.length];
    }

    if (numComponents == 1) {
      // Apply one LUT to all bands
      for (int i = 0; i < src.length; i++) {
        int s = src[i] - offset;
        if (s < 0) {
          throw new ArrayIndexOutOfBoundsException("src[" + i +
              "]-offset is " +
              "less than zero");
        }
        dst[i] = (int) data[0][s];
      }
    } else {
      for (int i = 0; i < src.length; i++) {
        int s = src[i] - offset;
        if (s < 0) {
          throw new ArrayIndexOutOfBoundsException("src[" + i +
              "]-offset is " +
              "less than zero");
        }
        dst[i] = (int) data[i][s];
      }
    }
    return dst;
  }

  /**
   * Returns an array of samples of a pixel, translated with the lookup
   * table. The source and destination array can be the same array.
   * Array <code>dst</code> is returned.
   *
   * @param src the source array.
   * @param dst the destination array. This array must be at least as long as <code>src</code>.  If
   * <code>dst</code> is <code>null</code>, a new array will be allocated having the same length as
   * <code>src</code>.
   * @return the array <code>dst</code>, an <code>int</code> array of samples.
   * @throws ArrayIndexOutOfBoundsException if <code>src</code> is longer than <code>dst</code> or
   * if for any element <code>i</code> of <code>src</code>, {@code (src[i]&0xff)-offset} is either
   * less than zero or greater than or equal to the length of the lookup table for any band.
   */
  public byte[] lookupPixel(byte[] src, byte[] dst) {
    if (dst == null) {
      // Need to alloc a new destination array
      dst = new byte[src.length];
    }

    if (numComponents == 1) {
      // Apply one LUT to all bands
      for (int i = 0; i < src.length; i++) {
        int s = (src[i] & 0xff) - offset;
        if (s < 0) {
          throw new ArrayIndexOutOfBoundsException("src[" + i +
              "]-offset is " +
              "less than zero");
        }
        dst[i] = data[0][s];
      }
    } else {
      for (int i = 0; i < src.length; i++) {
        int s = (src[i] & 0xff) - offset;
        if (s < 0) {
          throw new ArrayIndexOutOfBoundsException("src[" + i +
              "]-offset is " +
              "less than zero");
        }
        dst[i] = data[i][s];
      }
    }
    return dst;
  }

}
